This invention relates to identification of electrical arc faults and, more particularly, to methodology for identifying the occurrence of AC arc events.
Conventional electrical systems that utilize electrical wiring, equipment, and related interconnections may degrade with time, temperature, moisture, vibration, or other environmental conditions. Degradation of electrical wire insulation, for example, can result in electrical events that increase an operating temperature of the electrical system and, in extreme conditions, lead to fire.
Conventional electrical systems typically employ an electrical protection device to protect from such electrical events that typically result in relatively large spikes in electric current. A thermal circuit breaker, for example, trips to open the circuit when a current sensing element temperature exceeds a predetermined temperature level. Alternatively, a solid-state power controller (“SSPC”) monitors electrical current and trips if the current exceeds a preset energy rating.
Particular electrical events, such as electrical arcing, can be inherently low impedance and occur infrequently. This infrequent occurrence will prevent a thermal circuit breaker from reaching the predetermined temperature level or an SSPC from reaching a preset energy rating. As a result, conventional thermal circuit breakers and solid-state power controllers typically do not trip when an electric arc occurs, even though it is desirable to detect electric arc events for purposes such as identifying an electrical problem and preventing the problem from causing additional damage.
Several electrical protection devices attempt to address electric arc detection. An additional hard-wired arc-detecting circuit, for example, may be utilized in conjunction with the thermal circuit breaker to detect an AC electric arc and initiate a trip electro-mechanically. Likewise, an additional hard-wired arc-detecting circuit may be utilized in conjunction with a solid-state power controller to detect an AC electric arc and initiate a trip. Use of hard-wired circuitry may increase the size and weight of the electrical protection device and add expense.
Alternatively, other devices attempt to provide a “one size fits all” approach to identifying electrical arc faults. These types of devices purport to identify electrical arc events for both DC and AC electrical power by comparing electric current with known acceptable load currents and generate a fault signal if the comparison is undesirable. However, since DC and AC electrical power is inherently different, these devices and methodologies inherently overlook the differences between DC and AC in identifying electric arc faults. Furthermore, these devices and methodologies lack intelligence capability to accurately disregard transient electrical events, characterize an electrical arc event, or identify an arc event based on the DC or AC nature of the electrical current, for example.
Accordingly, there is a need for a compact, inexpensive, and intelligent device and methodology to identify AC electric arc events.